Currently, all screen will become the standard of high-end mobile phone, the border of the mobile phone is getting narrower, so the upper, lower, left and right borders of the display module have to be extremely narrow. Because the lower border (the LED side) has to keep a certain distance for light guiding, the difficulty of narrowing the lower border is increased, and the width of the conventional lower border is about 5 mm. As the requirements of the light source are higher, the area of the FPC of the light source is getting larger in order to dispose more LEDs, and the FPC of the light source is generally disposed on the top of the light guide plate. Therefore, the width of the FPC becomes a bottleneck of narrowing the lower border.